KR20080052384A - Control apparatus for continuously variable transmission - Google Patents

Abstract

A control device for a continuous transmission is provided to prevent a slip of a belt by supplying a primary pulley pressure based on an estimated current speed shift ratio. A primary pulley(2) and a secondary pulley(3) are arranged, such that V grooves of the primary and secondary pulleys are aligned with respect to each other in a V-belt type continuous transmission(1). V belts(4) are held on the V grooves of the primary and secondary pulleys. An engine(5) is arranged on a shaft of the primary pulley. A torque converter(6) and a forward/backward switch unit(7) are sequentially arranged from an engine side between the engine and the primary pulley. The torque converter includes a lock-up clutch. The forward/backward switch unit couples a sun gear with the engine through the torque converter and couples a carrier with the primary pulley.

Description

CONTROL APPARATUS FOR CONTINUOUSLY VARIABLE TRANSMISSION}

The present invention relates to a control device of a continuously variable transmission.

In a vehicle equipped with a continuously variable transmission, the belt is shifted between the primary pulley and the secondary pulley and shifted by changing the rotation radius of the belt in the primary pulley and the secondary pulley. At the time of braking and deceleration of the vehicle, the shift ratio is returned to the lowest level in preparation for the start of the next time after the stop, and the shift control is performed to stop after that. When the vehicle stops before the speed ratio returns to the lowest level during sudden braking and deceleration, the control is performed to return the speed ratio to the Low side after the start of the vehicle so that the speed ratio is suitable for the start of the next start. Patent Literature 1 discloses regulating the rate of change of the speed ratio to the Low side so that the belt does not slip during control.

In addition, as disclosed in Patent Literature 2, if the primary pulley pressure does not exceed the predetermined pressure even after a predetermined time elapses at the start of the vehicle, it is determined that there is a deviation between the stored pulley information and the actual transmission ratio, There is a control that makes it possible to oscillate by detecting whether the primary pulley pressure is increased by gradually displacing the stepper motor to an operation position corresponding to the high speed ratio, and setting it to an appropriate operation position.

[Patent Document 1] Japanese Patent Application Laid-open No. 63-074736

[Patent Document 2] Japanese Patent Application Publication No. 2004-125037

However, in the above invention, when the speed ratio is changed from a relatively high speed ratio to the Low side, there is a problem that the load applied to the belt at the time of oscillation becomes large, resulting in deterioration of the belt.

The problem is, for example, when the vehicle is stopped and the clutch is completely released, the primary pulley pressure is drained, the secondary pulley pressure is increased, and the winding position of the belt is set to the lowest position with these pulleys in the non-rotating state. Although this can be solved by displacing it, the hydraulic oil should be applied to the primary pulley before tightening the clutch to prevent slippage of the belt when the driver's oscillation request occurs while the control is not completely returned to the lowest level. It needs to be charged.

As in Patent Literature 2, in a continuously variable transmission in which hydraulic oil is rapidly supplied to the primary pulley by the positional relationship between the driving position of the stepper motor and the movable cone plate of the primary pulley, the driving position of the stepper motor is lower than the lowest position. Since the hydraulic oil of the primary pulley is set to be drained by displacing it into a position corresponding to the position of the primary pulley, in order to switch to the state of introducing the hydraulic oil into the primary pulley, the step motor is driven higher than the position corresponding to the current speed ratio. It is necessary to displace the position.

In the non-rotating state of the pulley, however, since the speed ratio cannot be calculated based on the relationship between the rotation speed of the primary pulley and the rotation speed of the secondary pulley, it is impossible to detect the current transmission ratio by these parameters.

At this time, if the sensor which detects the primary pulley pressure is provided like the continuously variable transmission of patent document 2, even if the current transmission ratio is not known, the drive position of the step motor will be moved to the High side until the primary pulley pressure becomes higher than or equal to a predetermined value. By displacing it, it is possible to fill hydraulic oil in a primary pulley.

However, in a continuously variable transmission without a sensor for detecting the primary pulley pressure, it is not possible to determine whether the primary pulley pressure is rising or not, and to the position where the primary pulley pressure can be supplied to the current transmission ratio. Since the stepper motor cannot be accurately displaced, there is a problem of impairing oscillation of the vehicle.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and in the vehicle stopped state, even if the primary pulley and the secondary pulley are in a non-rotating state while controlling to change the speed ratio toward the Low side, it is possible to accurately estimate the current speed ratio. It is an object of the present invention to prevent belt slippage in the event of an oscillation request to the vehicle during the control and to secure the oscillation performance of the vehicle.

In the present invention, the primary pulley on the input side of which the groove width is changed by the first hydraulic pressure, the secondary pulley on the output side of which the groove width is changed by the second hydraulic pressure, and the primary pulley and the secondary pulley are wound around the groove width. A belt having a belt in which the contact radius with the pulley is changed, while transmitting the rotational force transmitted from the output side of the vehicle through the frictional fastening element through the belt from the primary pulley to the secondary pulley, the speed ratio determined in relation to the contact radius In the continuously variable transmission control device for controlling the continuously variable transmission, the first hydraulic pressure is applied to the primary pulley according to the physical positional relationship between the shift actuator and the position of the movable flange of the primary pulley and the position of the shift actuator. Controlling the first hydraulic pressure by switching to the supply position, the position to discharge the first hydraulic pressure, the neutral position The shift control valve, the secondary pulley pressure control means for controlling the second hydraulic pressure, and the shift control valve for controlling the first hydraulic pressure to be approximately 0 when the frictional engagement element is released in the stopped state of the vehicle, and the second The secondary pulley pressure control means is controlled to increase the hydraulic pressure to a predetermined hydraulic pressure, and in the non-rotating state of the primary pulley and the secondary pulley, the contact radius with the primary pulley of the belt is reduced, and the contact radius with the secondary pulley is enlarged. Shift ratio control means for shifting the shift ratio toward the lowest level by displacing in the direction, immediately shift ratio storage means for storing the shift ratio immediately before the stop as the previous shift ratio, secondary pulley pressure detection means for detecting the second hydraulic pressure, and shift ratio control means The gear ratio ratio which integrates the gear ratio change amount calculated | required based on the detected 2nd hydraulic pressure during control by By the amount integrating means and, immediately before the speed ratio and the integrated speed ratio variation amount to the base provided with a gear ratio estimation means for estimating the transmission ratio of the transmission ratio control by the control means.

According to the present invention, in a vehicle stop state, the current pull ratio can be estimated accurately while the primary pulley and the secondary pulley are in a non-rotating state while controlling the shift ratio toward the Low side. When the oscillation request is made, the primary pulley pressure can be supplied on the basis of the estimated current transmission ratio, so that the belt can be prevented from slipping and the vehicle oscillation performance can be secured.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on drawing. Fig. 1 shows an outline of a V-belt continuously variable transmission (hereinafter referred to as a continuously variable transmission) 1, wherein the continuously variable transmission 1 has a primary pulley 2 and a secondary pulley 3 with both V grooves. It arrange | positioned so that it may be aligned, and the V belt (belt) 4 hangs on the V groove of these pulleys 2 and 3. A torque converter having an engine 5 disposed coaxially to the primary pulley 2 and having a lockup clutch sequentially from the side of the engine 5 between the engine 5 and the primary pulley 2 ( 6) and forward / backward switching mechanism (friction fastening element) 7.

The forward and backward switching mechanism 7 uses the double pinion planetary gear set 7a as a main component and couples the sun gear to the engine 5 via the torque converter 6, and the carrier pulley 2 ) The forward and backward switching mechanism 7 further includes a forward clutch 7b directly connected between the sun gear and the carrier of the double pinion planetary gear set 7a and a reverse brake 7c for fixing the ring gear. The input rotation via the torque converter 6 from the engine 5 is transmitted to the primary pulley 2 as it is at the time of fastening the 7b, and the torque converter from the engine 5 at the time of fastening the reverse brake 7c. The rotation of the input via (6) is reversed and transferred to the primary pulley (2).

The rotation of the primary pulley (2) is transmitted to the secondary pulley (3) via the V belt (4), and the rotation of the secondary pulley (3) is then output shaft (8), gear jaw (9) and differential gear device It is transmitted to the wheel via (10).

In order to be able to change the rotation transmission ratio (shift ratio) between the primary pulley 2 and the secondary pulley 3 during the above power transmission, the V grooves of the primary pulley 2 and the secondary pulley 3 are changed. One of the cone plates to be formed is the fixed cone plates 2a and 3a and the other cone plates 2b and 3b are movable cone plates (moving flanges) which can be displaced in the axial direction. These movable cone plates 2b and 3b use the primary pulley pressure (primary hydraulic pressure) Ppri and the secondary pulley pressure (second hydraulic pressure) Psec generated by the line pressure as the primary pressure to the primary pulley chamber 2c and By supplying to the secondary pulley chamber 3c, it is pressed toward the fixed cone plates 2a and 3a, thereby frictionally coupling the V belt 4 to the cone plate, between the primary pulley 2 and the secondary pulley 3. Power transmission.

At the time of shifting, the V groove widths of both pulleys 2 and 3 are changed by the differential pressure between the primary pulley pressure Ppri and the secondary pulley pressure Psec generated corresponding to the target speed ratio I (o). By changing the diameter of the winding arc of the V-belt 4 with respect to the pulleys 2 and 3 continuously, the actual speed ratio ip is changed to realize the target speed ratio I (o).

The primary pulley pressure (Ppri) and the secondary pulley pressure (Psec) are connected to the output of the hydraulic pressure of the forward clutch (7b) for tightening when the forward travel range is selected and the reverse brake (7c) for tightening when the reverse travel range is selected. Together, it is controlled by the shift control hydraulic circuit 11. The shift control hydraulic circuit 11 performs control in response to a signal from the transmission controller 12.

The transmission controller 12 has a signal from the primary pulley rotation sensor (primary pulley rotation speed detecting means) 13 which detects the primary pulley rotation speed Npri, and the secondary which detects the secondary pulley rotation speed Nsec. A signal from the pulley rotation sensor (secondary pulley rotation speed detecting means, vehicle speed detecting means) 14 and a signal from the secondary pulley pressure sensor (secondary pulley pressure detecting means) 15 that detects the secondary pulley pressure (Psec); , The signal from the accelerator opening sensor 16 for detecting the accelerator pedal depression amount APO, the selected range signal from the inhibitor switch 17, and the oil temperature sensor 18 for detecting the shift operation oil temperature TMP. Signals from the engine controller 19 and the input torque Ti from the engine controller 19 responsible for control of the engine 5 (engine rotational speed and fuel injection time), and from the acceleration sensor 20 It is input.

Next, the shift control hydraulic circuit 11 and the transmission controller 12 will be described using the schematic configuration diagram of FIG. First, the shift control hydraulic circuit 11 will be described below.

The shift control hydraulic circuit 11 includes an oil pump 21 driven by an engine, and a predetermined line pressure is supplied by the pressure regulator valve 23 to the pressure of the hydraulic oil supplied to the oil passage 22 by the oil pump 21. Adjust to (PL). The pressure regulator valve 23 controls the line pressure PL in accordance with the driving duty to the solenoid 23a.

The line pressure PL of the oil passage 22 is regulated by a pressure reducing valve (secondary pulley pressure control stage) 24 on one side, and supplied to the secondary pulley chamber 3c as the secondary pulley pressure Psec, and shifted on the other side. It is pressure-controlled by the control valve 25, and is supplied to the primary pulley chamber 2c as a primary pulley pressure Ppri. The pressure reducing valve 24 controls the secondary pulley pressure Psec in accordance with the driving duty to the solenoid 24a.

The shift control valve 25 has a neutral position 25a, a boosting position 25b, and a depressurization position 25c, and the shift control valve 25 has an intermediate position in the shift link 26 to switch these valve positions. Connect to The shift link 26 connects the step motor 27 as a shift actuator to one end and the movable cone plate 2b of the primary pulley 2 to the other end.

The step motor 27 becomes an operation position advanced by the number of steps corresponding to the target speed ratio I (o) from the home position, and the shift link 26 is moved by the operation of the step motor 27. By swinging the connecting portion with 2b as a supporting point, the shift control valve 25 is moved from the neutral position 25a to the boosting position 25b or the depressurizing position 25c. As a result, the primary pulley pressure Ppri is increased by increasing the line pressure PL to the original pressure, or the pressure is reduced by the drain, and the differential pressure with the secondary pulley pressure Psec is changed, thereby upshifting to the high side speed ratio or A downshift to the low side speed ratio occurs, and the actual speed ratio (hereinafter referred to as speed ratio) ip changes to follow the target speed ratio I (o).

The progress of the shift is fed back to the corresponding end of the shift link 26 via the movable cone plate 2b of the primary pulley 2, and the shift link 26 controls the shift with the connection point with the step motor 27 as a supporting point. The valve 25 is swung in the direction of returning from the pressure increasing position 25b or the pressure reducing position 25c to the neutral position 25a. Thereby, when the target speed ratio I (o) is achieved, the shift control valve 25 can be returned to the neutral position 25a to maintain the target speed ratio I (o).

The solenoid drive duty of the pressure regulator valve 23, the solenoid drive duty of the pressure reducing valve 24, and the shift command (the number of steps) to the step motor 27 are the forward clutch 7b and the reverse brake 7c shown in FIG. Is carried out by the transmission controller 12 together with control of whether or not to supply the fastening hydraulic pressure. The transmission controller 12 is comprised by the pressure control part 12a and the speed change control part 12b.

The pressure control unit 12a determines the solenoid drive duty of the pressure regulator valve 23 and the solenoid drive duty of the pressure reducing valve 24, and the shift control unit 12b determines the attained shift ratio DsrRTO and the target shift ratio I (o). To calculate.

When the vehicle stops, the arrival speed ratio DsrRTO is calculated along with the decrease in the vehicle speed, and the target speed ratio I (o) is obtained based on the arrival speed ratio DsrRTO.

When the vehicle stops, the speed shift ratio DsrRTO is set to the low side in response to the decrease in the vehicle speed, and thus the target speed ratio I (o) is also set to the low side, and the step motor 27 sets the target speed ratio I ( o)], specifically, the shift ratio control valve 25 is displaced to a position where the decompression position 25c is used. As a result, the vehicle is stopped by downshifting so that the transmission ratio ip finally reaches the lowest level.

In addition, while traveling, the primary pulley rotation speed Npri detected by the primary pulley rotation sensor 13 is determined by the secondary pulley rotation sensor 14 in a constant calculation cycle (for example, every 10 ms). The transmission ratio ip is obtained by dividing by the detected secondary pulley rotational speed Nsec. When the vehicle speed becomes less than the predetermined value (first predetermined value, for example, 3 km / h), or when the primary pulley rotation speed Npri becomes less than the predetermined value (second predetermined value, for example, 200 rpm) It is determined that the vehicle is immediately before the stop, and the shift ratio ip obtained in the operation cycle immediately before the predetermined cycle is stored as the shift ratio ips immediately before the stop. In addition, the speed ratio ips just before stopping may store the computed value before several cycles instead of the computed value of the speed ratio ip of the immediately preceding cycle.

The vehicle may stop before the transmission ratio ip reaches the lowest, but in such a case, the clutch is completely released while the vehicle is stopped, the primary pulley pressure Ppri is completely drained, and the secondary pulley pressure is completely removed. Low return control is performed to raise (Psec) to a predetermined pressure. Thereby, even when the primary pulley 2 and the secondary pulley 3 are not rotating, the movable cone plates 2b and 3b move, and the winding arc of the V belt 4 in the primary pulley 2 is moved. The diameter becomes small, and in the secondary pulley 3, the diameter of the winding arc of the V belt 4 becomes large. Thus, the relative position of the primary pulley 2 and the secondary pulley 3 is changed, and the transmission ratio determined by the relationship between the winding arc diameter of the primary pulley 2 and the secondary pulley 3 is changed to the Low side.

As described above, when the vehicle stops before the speed ratio ip becomes the lowest, the low-speed control is performed so as to set the speed ratio ip of the continuously variable transmission 1 to the lowest. It is possible to oscillate from the state where ip) becomes the lowest.

In addition, when the vehicle is required to start during the low return control, if the primary pulley pressure Ppri can be detected as in the configuration of Patent Document 2, the current transmission ratio can be estimated. Although it is possible to displace the stepper motor 27 to the position necessary to supply hydraulic pressure suitable for the primary pulley 2, the transmission ratio cannot be estimated in the continuously variable transmission in which the primary pulley pressure sensor is not provided. Therefore, it becomes impossible to displace the step motor 27 to an appropriate position. If the stepper motor 27 cannot be displaced to an appropriate position, the forward and backward switching mechanism 7 transmits power from the engine 5 while the primary pulley pressure Ppri is drained by the low return control. There is a fear that the V-belt 4 slips. Hereinafter, the low return control which solves such a problem is demonstrated in detail using the flowchart of FIG. The following control is performed every predetermined time.

In step S100, it is determined whether the Low return control start condition is satisfied. When the low return control start condition is satisfied, the stored shift speed ratio ips is read and the flow proceeds to step S101, and when the low return control start condition is not satisfied, the control ends (step S100). Constitutes a previous speed ratio storage means).

The case where the low return control start condition is satisfied is when the vehicle is completely stopped, the shift range is N range, and the shift ratio ip is higher than a predetermined value (for example, 2.0), that is, the speed ratio This is the case where the vehicle stops before power is changed to the low-side transmission ratio of the degree where oscillation is possible, and power is not transmitted from the engine 5. In addition, the vehicle stops completely, and since the brake is operating, there is no accelerator operation, and the vehicle speed may be determined based on a parameter such as less than a predetermined vehicle speed (for example, 1 km / h). In addition, in order to satisfy that the power from the engine 5 is not transmitted, the fastening of the forward clutch 7b (retraction brake 7c) may be conditionally released. The vehicle speed is calculated based on the secondary pulley rotation speed Nsec.

In step S101, the operation position of the step motor 27 is set to the position that is mechanically at the Low side rather than the lowest position, and the drain of the primary pulley pressure Ppri is started. In this embodiment, it drains until the primary pulley pressure Ppri becomes substantially zero.

In step S102, oil is supplied to the secondary pulley chamber 3c to raise the secondary pulley pressure Psec. In this embodiment, the secondary pulley pressure Psec is made high until predetermined pressure P1 preset. The predetermined pressure P1 is a pressure that becomes the strength limit of the V belt 4. By starting the drain of the primary pulley pressure Ppri in step S101 and raising the secondary pulley pressure Psec in step S101, the pulleys 2 and 3 are in a non-rotating state, but the speed ratio ip gradually increases to the maximum. It changes toward Low (step S101 and step S102 comprise a speed ratio control means).

In step S103, the secondary pulley pressure sensor 15 detects the secondary pulley pressure Psec.

In step S104, the gear ratio ratio change ratio dip is calculated from FIG. 4 from the secondary pulley pressure Psec detected in step S103. 4 is a map showing the relationship between the secondary pulley pressure Psec and the shift ratio change ratio (shift ratio change amount) dip when the primary pulley pressure Ppri is drained and the secondary pulley pressure Psec is increased. When the pulley pressure Psec is increased, the speed ratio change rate dip becomes large.

In step S105, the current estimated speed ratio ic is calculated by adding the speed ratio change ratio dip calculated by step S104 to the estimated speed ratio ic calculated last time. The estimated speed ratio ic is calculated by adding the speed ratio change ratio dip calculated in Step S104 to the speed ratio ip just before starting the low return control, that is, the stored speed ratio ips just before the stop (step S105 is calculated). The speed ratio change amount integration means and the speed ratio estimation means).

In step S106, it is determined whether the low return control completion condition is satisfied. When the low return control completion condition is not satisfied, the process proceeds to step S107. When the low return control completion condition is satisfied, the process proceeds to step S108.

The case where the low return control completion condition is satisfied is when the state in which the primary pulley pressure Ppri is completely drained and the secondary pulley pressure Psec reaches the predetermined pressure P1 continues for a predetermined time or is estimated This is the case when the speed ratio ic becomes the lowest.

In step S107, it is determined whether the Low return control stop condition is satisfied. When the low return control stop condition is satisfied, the process proceeds to step S109. When the low return control stop condition is not satisfied, the process returns to step S101 and the control is repeated.

The case where the low return control stop condition is satisfied is when the shift lever is operated in the D range or the R range and the accelerator pedal is pressed, the vehicle speed is greater than the predetermined vehicle speed, and the like.

When the low return control completion condition is satisfied by Step S106, the relative position of the primary pulley 2 and the secondary pulley 3 is mechanically more than the position where the speed ratio ip becomes the lowest or the lowest. This is the position when the gear ratio on the low side is reached. In step S108, the operation position of the step motor 27 is set to the position where the speed ratio ip becomes the lowest, and the secondary pulley pressure Psec is set to the pressure when the speed ratio ip becomes the lowest. As a result, the vehicle can be started from the state where the transmission ratio ip becomes the lowest during the next start of the vehicle, and the starting performance of the vehicle can be improved.

In step S109, since the low return stop condition is satisfied by step S107, that is, an oscillation request is made during the low return control, the position corresponding to the estimated speed ratio ic calculated by step S105 is determined by the step S105. It is set as the position (predetermined position) on the High side by a predetermined amount. Further, the secondary pulley pressure Psec is set to a pressure for realizing the estimated shift ratio ic (step S109 constitutes a shift actuator control means).

This makes it possible to reliably supply the primary pulley pressure Ppri by setting the speed change control valve 25 to the boosting position 25a. Even if the power from the engine 5 is transmitted, the V belt 4 does not slide. It is possible to secure the oscillation property of the vehicle by keeping it.

By the above control, the estimated speed ratio ic is calculated on the basis of the secondary pulley pressure Psec during the low return control, so that the estimated speed ratio ic is determined even when the vehicle starts to be requested while the low return control is being performed. Based on the primary pulley pressure (Ppri) can be controlled. Therefore, even when the vehicle has a start request during the low return control, the vehicle can be started quickly by appropriately controlling the primary pulley pressure Ppri and the secondary pulley pressure Psec according to the estimated transmission ratio ic. .

In addition, this control can be used also for a vehicle using an oscillation clutch without using the torque converter 2, and when an oscillation clutch is used, it is preferable to perform Low return control quickly.

The calculation of the estimated speed ratio ic may be started after the primary pulley pressure Ppri becomes completely zero. Thus, the estimated speed ratio ic is estimated to be higher than the actual pulley ratio, and when the low return control is stopped and the operating position of the step motor 27 is set based on the estimated speed ratio ic, The primary pulley pressure Ppri can be reliably supplied, and the slippage of the V belt 4 can be suppressed.

The effect of embodiment of this invention is demonstrated.

In the present embodiment, the primary pulley pressure Ppri and the secondary pulley pressure Psec are controlled while the primary pulley 2 and the secondary pulley 3 are not rotated while the vehicle is stopped. When the speed ratio determined in relation to the winding arc diameter of the secondary pulley 3 is changed to the low side, the estimated speed ratio ic is calculated based on the secondary pulley pressure Psec. Thereby, the transmission ratio during the low return control can be estimated without using the primary pulley pressure sensor, and even when the vehicle is requested to start during the low return control, the primary pulley pressure is based on the estimated transmission ratio ic. (Ppri) can be supplied. Therefore, when the vehicle starts to be driven during the low return control, the V-belt 4 can be kept from slipping to ensure the vehicle's oscillation property.

When the pulley ratio of the primary pulley 2 and the secondary pulley 3 is changed to the low side, the primary pulley pressure Ppri is completely drained and the secondary pulley pressure Psec is raised to a predetermined pressure P1. In this way, the speed ratio can be changed quickly during stopping.

When the vehicle starts to be requested during the low return control, the primary pulley pressure Ppri can be reliably supplied by shifting the operation position of the step motor 27 to the higher side than the estimated speed ratio ic, so that the V belt ( 4) to keep the vehicle from slipping to ensure the vehicle's oscillation property.

This invention is not limited to the above-mentioned embodiment, Of course, various changes and improvement which can be achieved within the range of the technical idea are included.

1 is a schematic configuration diagram of a continuously variable transmission of an embodiment of the present invention.

2 is a schematic configuration diagram of a shift control hydraulic circuit and a transmission controller according to an embodiment of the present invention.

3 is a flowchart for explaining Low return control according to the embodiment of the present invention;

4 is a map showing the relationship between the primary pulley pressure and the speed ratio change rate of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: continuously variable transmission

2: primary pulley

2b: movable cone plate (moving flange)

3: secondary pulley

4: V belt (belt)

7: forward and backward switching mechanism (friction fastening element)

13: primary pulley rotation sensor (primary pulley rotation speed detection means)

14: secondary pulley rotation sensor (secondary pulley rotation speed detection means, vehicle speed detection means)

15: secondary pulley pressure sensor (secondary pulley pressure detection means)

24: pressure reducing valve (secondary pulley pressure control means)

25: shift control valve

27: step motor (shift actuator)

Claims (3)

A primary pulley on the input side for changing the groove width by the first hydraulic pressure, Secondary pulley on the output side that changes the groove width by the second hydraulic pressure, It has a belt wound around the primary pulley and the secondary pulley, the contact radius of the pulley changes in accordance with the groove width, Stepless control of the continuously variable transmission in which the rotational force transmitted from the output side of the engine of the vehicle through the friction fastening element is transmitted from the primary pulley to the secondary pulley through the belt, and the transmission ratio determined in relation to the contact radius is changed steplessly. In the control device of the transmission, With shift actuator, According to the physical positional relationship between the position of the movable flange of the primary pulley and the position of the shifting actuator, the switching to the position for supplying the first hydraulic pressure to the primary pulley, the position for discharging the first hydraulic pressure, the neutral position A shift control valve for controlling the first hydraulic pressure; Secondary pulley pressure control means for controlling the second hydraulic pressure, When the frictional engagement element is released in the stopped state of the vehicle, the shift control valve is controlled to set the first hydraulic pressure to approximately 0, and the secondary pulley pressure control means is configured to raise the second hydraulic pressure to a predetermined hydraulic pressure. In the non-rotating state of the primary pulley and the secondary pulley to shift the contact radius of the belt with the primary pulley in a reduction direction, and to shift the contact radius of the secondary pulley in an enlarged direction. Speed ratio control means for changing the speed ratio toward the lowest level; A previous speed ratio storage means for storing the speed ratio just before the stop as a previous speed ratio, Secondary pulley pressure detecting means for detecting the second hydraulic pressure; A speed ratio change amount integrating means for integrating a speed ratio change amount determined based on the detected second oil pressure during the control by the speed ratio control means; And a speed ratio estimating means for estimating a speed ratio during the control by the speed ratio control means on the basis of the immediately previous speed ratio and the accumulated speed ratio change amount. The shift position of the shift actuator is shifted to a predetermined position higher than the position corresponding to the shift ratio estimated by the shift ratio estimating means when the control is stopped during the control by the shift ratio control means. And a transmission actuator control means for controlling the continuously variable transmission. The vehicle speed detecting means according to claim 1 or 2, Primary pulley rotational speed detection means for detecting the rotational speed of the primary pulley, Secondary pulley rotational speed detecting means for detecting the rotational speed of the secondary pulley, The previous speed ratio storing means calculates a speed ratio from the relationship between the primary pulley rotational speed and the secondary pulley rotational speed every predetermined cycle, and when the vehicle speed is equal to or less than the first predetermined value, or when the primary pulley rotational speed is zero, 2, when at least one of the values is equal to or less than the predetermined value, the transmission ratio before the predetermined cycle is stored as the immediately preceding transmission ratio. The control apparatus for a continuously variable transmission.

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